Generally, moisture evaporated from food products condenses on the inner surface of a film used for packaging a variety of water-containing food products, such as raw meats, minced meats, hams, sausages, fresh vegetables, seafoods, other processed food products, etc., thereby resulting in poor visibility of the packed food products. Therefore, to prevent this disadvantage, an anti-fogging property is one of the attributes expected of the film. Especially, when raw meats, minced meats and the like are packed at a store counter and immediately put in a showcase for sale, the anti-fogging effect must work immediately. In such a case, the temperature in the showcase ranges from about −5° C. to about 5° C. Although the temperature at which fresh vegetables and the like are stored in the showcase varies depending on the kind of item being displayed, it is generally higher than that for raw meats, ranging from about 0° C. to about room temperature.
When a stretched, multilayer film is used, the desired anti-fogging effect cannot be obtained due to disadvantages caused by stretching of the film, use of additives in the anti-fogging layer, migration of an anti-fogging agent provided in inner layers to outer layers when the film is stored in a roll, etc. Further, it is difficult to attain an immediate anti-fogging effect.
Japanese Unexamined Patent Publication No. 52334/1995 discloses a resin film having an anti-fogging agent and an anti-slip agent incorporated therein. The heat-seal layer of the film disclosed therein contains an anti-fogging agent in an amount of 3,000 to 13,000 ppm and an anti-slip agent in an amount of 3,000 to 13,000 ppm, requiring improvements in its anti-fogging property, stretchability, etc.
In view of the above-described state of the art, an object of the present invention is to provide a film that can exhibit a quick-acting, anti-fogging property immediately after being used for packing at a store counter and that can preserve the commercial value of packed products attractive to consumers.